Application of sunscreen is a widely used mechanism for protecting skin from the harmful effects of UV light. However, protection can only be achieved through effective application, and areas that are routinely missed are likely at increased risk of UV damage. Here we sought to determine if specific areas of the face are missed during routine sunscreen application, and whether provision of public health information is sufficient to improve coverage. To investigate this, 57 participants were imaged with a UV sensitive camera before and after sunscreen application: first visit; minimal pre-instr These data reveal that a public health announcement-type intervention could be effective at improving coverage of high risk areas of the face, however high risk areas are likely to remain unprotected therefore other mechanisms of sun protection should be widely promoted such as UV blocking sunglasses. This work was supported by bench fees raised from a University of Liverpool Masters in Research Course. Introduction Despite increasing sun awareness and sun protection usage, between 70–90 percent of basal cell carcinomas (BCCs) develop in sun-exposed head and neck regions, and 5 to 10 percent of all skin cancers occur on the eyelids alone[ 1 ]. Specifically within England, 33610 eyelid BCCs were recorded in the 11 years between 2000 and 2010[ 1 ]. Within the eyelid area, the medial canthus, a region where the medial corner of the upper and lower eyelids meet, has been shown to be not only a particularly common site for BCC, but is also associated with poor prognosis [ 2 , 3 , 4 , 5 ]. It has been postulated that the high prevalence of non-melanoma skin cancer on the eyelids is due to the skin being the thinnest on the body and hence specifically vulnerable to damage from prolonged ultraviolet (UV) light exposure, a well-established risk factor for BCCs and for squamous cell carcinomas [ 6 , 7 , 8 , 9 , 10 ]. Therefore, the importance of adequately protecting this vulnerable area is clear, and the use of sunscreen formulations has been widely promoted. Use of sunscreens for sun protection requires two conditions to be met: i) adequate quantities of the substance to be applied with appropriate frequency of reapplication, and ii) effective coverage of all sun exposed areas. However, the positive health benefits of UV exposure in terms of supporting the complex sensory functions of the skin, including effects on brain, neuroendocrine, and immune function, as well as the deleterious effects of vitamin D insufficiency have been widely demonstrated leading to guidelines designed to balance the benefits of UV exposure against the potential DNA damage [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Therefore an updated investigation into application habits is warranted. Recent data suggest that sunscreens are increasingly becoming the method of choice for sun protection meaning that it is more important than ever that sunscreen is applied effectively [ 24 , 25 , 26 ]. UV photographic imaging has thus been demonstrated as being useful as a method not only to assess sunscreen application but also to assess skin damage and drive behavioral change in sun bed users [ 30 , 31 , 32 ]. In this study, we have adopted the UV imaging approach to determine if skin cancer prone facial regions are ineffectively covered, and if an information based intervention could be used to improve sunscreen application. Materials and methods Ethical approval The study was approved by University of Liverpool Ethics Review Board with approval number 201606181. Written consent was obtained from all participants prior to both phases of the trial. Mann-Whitney tests were performed to compare coverage between eyelid regions and non eyelid regions relative to gender, skin type, and sun cream versus sun spray. Spearman’s correlation was used to assess correlation between percentages of eyelid regions missed with percentage of rest of face. Wilcoxon tests were used to assess the improvement in coverage. Chi square test was used to assess change in medial canthal region coverage. Differences were deemed statistically significant where p<0.05. Note the dark spots indicating presence of UV damaged skin i.e, areas of pigmentation deep in the dermis that are invisible to the naked eye but visible to UV photography. As the periorbital/medial canthal regions (magenta box in Fig 1C ) are particularly at risk for more aggressive BCC [ 2 , 38 , 39 ], a secondary binary analysis (covered/not covered) was performed on this region, revealing that 44 of the 57 failed to cover this region ( Fig 2E ). In addition to its use for identifying sunscreen application, UV photography also enables the visualization of areas of existing sun damage in lighter complexion individuals. Careful examination of our before sunscreen application images revealed numerous examples of sun damage spots in eyelid regions supporting the concept that this area is at risk for sun damage ( Fig 1F ). Provision of simple risk indication information improved the sunscreen coverage of eyelid regions Next we sought to determine if increased awareness of eyelid cancer risk would be sufficient to drive an improved coverage of the at risk areas. Various methods of behavioural intervention to promote sun-protection have been previously reported, with varying levels of success. First; one would predict that our cohort would have a base line cancer-risk awareness levels If sunscreen application is only performed when preparing for an extended period in the sun, ineffective application will lead to a false sense of security in terms of perceived protection. Our data strongly indicate that in routine application, the eyelid region and particularly the medial canthal areas are relatively poorly protected hence at increased risk. The belief that the whole face is protected may repeatedly increase UV exposure to vulnerable areas that have been missed as people spend longer exposed to the sun.